Manufacture of a finely-divided dry soap product



* March 2g, 192;? v 152115116..

R. L'. HOLLIDAYV liNUfAcu:umaV of A www Dlvwn DRY .SGAF'PRODW Filed Amm la 1921sv originazl Filed April 19J ame,

ATTORNEY Patented 2.2-, I

UNIT

1,621,5tslf normar L. nommer, or Naw ING"GOBPOBATION, QF `N'EW YORK, N

YoaxfN. Y., AssIGNoa roINDUsrm-AL sur-nir- Y., a conroaarroN or vanwaar.

lnamnaae'rUma: or A -rINELY-mvmnn DRY soar rnoDUc'r.

t.lippimaami' mea April 1a, 192s. semi no. 102,860. H

The present invention relates to the manufacture of a finely divided dry soap product.

and has to do particularly with amanner of preparing Athe soap stock to render it suitable for conversion mto dry form and the conversion of such stock into dry form in such a manner that all of the conditions of the process are subject to accurate control.

In the` common process of soap manufacture the fats andoils are sapomied by the action of a caustic alkali such as, for example, sodium-hydroxide. The usual practice is to' cook orboil the' fatty material in the presence of a proper amount of caustic ma# terial until the desired reactions have taken place.` After the completion of the boiling operation and any other treatment which may be necessary, dependlng upon the character of the raw materials used, the kind of soap desired; etc., the hot semi-liquid soap paste is crutched to reduce it to a thoroughly mixed homogeneous mass and to incorporate uniformly into it any filler or. added material which may be desired 1n thev finished soap, after which the soap is placed in racks or frames where -it remains until it solidifies. After solidiication the blocks of soap are slabbed and cut into cakes, the cakes are surface dried to facilitate handling and the driedv cakes are then pressed to put them in condition for packagin In the manufacture of toilet :soaps the ried cakes ar e usually chip ed to reduce them to flake form and the Hak matter, perfume, and the like, to produce a .uniform homogeneous soap which is then plodded, to convert it into a continuous bar which may be cut into cakes of any length and then stamped or pressed as desired. 1

A particular diiiculty in the soap manufacturing process lies in effecting solidification of the soa A period of days'is required for solidificationof the soap in bulk. In the manufacture gf' milled toilet soaps solidification of the boiled soap is sometimes l facilitated by placing the soap mass on an 'endless belt which. slowly conveys it. through a drying .chamberwherein air is circulated about the soap until it is reducedvto solid form in condition for milling. In gthe production of soap iiakes the soapstock is commonly solidified "on rolls and scraped off or ribboned land dried:- 'Different portions es are milled with coloringv of the soap produced in this way show, in

the ordinaryV manufacturing run, a rather Awlde varlatlon in moisture content.l In the and to dition through the atmosphere until the particles or fragments of the soa paste are solidified. The action which tes place is largely a cooling and solidifying actlon, but some evaporation =of moisture from Atheso'a takes place by reason of its passage througii the air and by reason of thel contained heat of the soap itself. The diiculty with this lprocess is that, in the short time available for solid'iication -and with the conditionsthat are attained in practical operation, the soa does not, in fact, solidify satisfactoril and, although the initial soap paste or stoc is as heavy ascan reasonably be produced during the process of manufacture, the soap invariably masses and cakes in a moist condition and is not produced as a relatively fine powder composed ofnon-adherin particles. To aid. 1 in evaporatingI the i uid from the soap paste it has been propo to subject the boiled soap to high pressure and to heat it at such pressure, before admittingv it to atmos heric conditions, to a temperaturev well albove its boilin temperature at atmospheric pressure.v Wren this highly heated soap is released to atmosphere a certain.amount of evaporationtakes place due to the'excess `of `sensible heat contained in the paste over that which it can contain at` l atmospheric pressure. process, however, 1s subjectl to the disadvantages 'ust noted and is not successful inthe p uc tion 'of' a powdered soap.

It has further been proposed to modify this process by introducing to the heated soap paste as it is released to atmospheric v conditions a quantity'of superheated steam `or drying air for the purpose of effecting the necessary evaporationf'and it has also been proposed to heat'the air of the room .or cham er into which the Asoap is sprayed to thus furnish an appropriate amount of heat to effect the desired evaporation. These latter proposals have not proven successful for the reason that the presence in the room of the moisture evaporated from the soap prevents satisfactory collection of the soap in the form of a dry powder, in addition tothe fact that no systematic control ofl humidity conditions and consequent moisture content in the finished soap product is obtainable. Tt has further been proposed to disintegrate or break up soap paste drawn from the boiling kettles into relatively small fragments and to drop these fragments of soap paste against and through a rising cui'- rent of air to effect solidification of the particles and thus to'prdduce a dry soap product of granular nature made up of irregular particles or fragments. This process is open to a number of objections such as the fact that the heavier fragmentsn pass through the apparatus in a shorter time and consequently with less drying treatment than do the lighter fragments with the result that different portions of the dried soap product contain rather widely different amounts of moisture, the loss of a large amount of the light soap fragments if the soap is disintegrated to reasonably tine condition and if any substantial amount of air 1s used, the

variation of operating conditionsdue to changes in atmospheric conditions and the practical impossibility of successfully operating tlie process to satisfactorily produce a dry solid product under certain atmospheric conditions, such as on hotl humid summer days. This process is not at all successful if an attempt is made to heat the treating air for the reason that the treated soap fragments Contact with the air at its highest temperature at substantially thev time they leave the apparatus so that it is practically impossible to collect the particles in solidified state unless theirwat-er content is reduced fai" below that which is desired in the finished soap. l

iIt is a particular object of thi's invention to provide a process for`tlie production of a powdered soap by which the soap can successfully be produced directly in the form of a dry, non-sticking powder of relatively small particle size and of reasonably regular particle shape and structure and having a moisture content which is readily controllable over a wide range amply covering all of the requirements of the various kinds of commercial soap products. This is accomplished in the present invention by the manner of prepa-ring the initial soap stoclri'rnd particularly by themethod which is einployed in reducing the soap stock to solid form.

The initial soap stock is prepared in free iowing condition rather than'in the form of a heav`y semi-liquid paste as is fre uently done in the manufacture of soap. hor inin such condition that it may readily be broken up into a fine spray of liquid particles of relatively uniform size and structure so that a corresponding degree o f rcasonable uniformity and regularity of parti-` cle size and sti'ucture in the ultimate product is obtained. The spraying or disintegrating ot' the liquid soap is preferably conducted at temperatures of from. 1500. to 250 F., and it is under suoli temperature conditions that the soap stock should be in liquid free flowing condition. The essential requirement of this part. of the process is that the soap' be reduced to a condition which is 'sufhciently uid to permit breaking up of the liquid mass into the form of a-fine spray, the particles of which are essentially liquid particles of the same general order of magnitude in size and of regular generallyl spherical shape similar to the particles of a sprayed liquid as contrasted with the beaten up or shredded particles o r fragments of a heavy semi-liquid paste whereinltlie particles are entirely irregular in shape and do not tend definitely toward any specific configuration.

After the soap stock has once been disintegrated in proper fashion it is important that it be treated in such manner as to produce the type of solid product desired and to permit of systematic and controllable variation of conditions so that the character of theultimate product in turn may be controlled. The present process aecomplishes lt-he drying and the solidification vof the soap particles under definitely controlled conditions while the particles are maintained in suspension-in ay gas. A number of requirements are necessary fto accomplish these results. It is important that the particlesof soap stock be treated in a current of circulating gas which carries away the moisture evaporated from the particles and flows in such fashion that, when continued operation of the apparatus has been established, the conditions of the process such as humidity, temperature, state of dryness of the soap particles, etc., at 'any given-place in the drying tower are, for all practical purposes` substantially constant. important that the current of gas in which the soap particles are treated be passed through the drying tower in a commonI di- It is also rection of flow with the soap'particles so..

a definite and regular manner. With this arrangement'V the gas first contacts'with the soapv particles at substantially its highest,v ,tem erature and last contacts with the slidi ed soapv particlesat substantially its lowest temperature. The particles under treatment arc carried through the tower in a positive fiow, and thus all of the particles remain in the drying tower for substantially the saine length ot time and are subjected to substantially identical treatment. With this ondition existing the air current may be .controlled and conditionedas to rate of iow, volume, temperature, moisture content, and the like, so that any desired variations in the ultimate product may bei obtained by variation of one orall of these variables.

. The process also provides for removing the treated soap particles together withthe gas" which carries them, as well as the moisture contained in it, from the drying tower in carried insuspension cooling gas may be admitted as desired along the length of the tower sothat after 'the soap particles have been reduced to a desired moisture content they may also be suitably reduced in--temperature to assure their production in nonsticking form whereby the soap product will be a finely divided regular apparently dry free flowing powder. The .present process therefore provides vfor a uniform treatment of the particles of'soap stock to uproduce a uniform product which maybe controlled to possessuwithin reasonable limits any desii-ed moisture content and which may be successfully and easily produced commercially at all times and in all` weather conditions in the form of anfapparently dry solid easily handled 'powder product.

The accompanying drawing illustrates more or less diagrammatically an apparatus in which the present process may be carried out as a continu'ous operation. The soap stock, after havin been produced in the usual course of te manufacture of the product and having been prepared with a sufficient amount of water to adapt it for treatment by the present process, is delivered to a tank 1 provided with anagitator 2- driven continuously by motor 3 for the Y purpose of maintaining the entii'ebofly of stock iii a-thoroiiglily mixed homogeneous condition. The tankf1 is steam' jacketed as indicated at 4 for the purpose of maintaining the steek ata suitable temperature. The liquid stock from the tankA 1 is passed through line 5 into the drying tower'v 6. The

breaking up or spraying of the liquid stockl `mon direction of iow an into the 'form of small uniformly consti- -4 tuted particles is effected by means of s ray nozzles 7 lecated in the upper part the drying tower 6 and arranged about the tower iii such 'fashion -as tuniformly'distribute the spray throughout the entire 'upper portion of the tower. VIn the apparatus here shown tlie flow of soap` to the nozzles 7 occurs due to gravity, and the breaking up of the material into the form of a spray .1s effected by means of means of atomizing air or steam sup lied to the nozzles 7 a's'indicated at 8. he drying gas consists of at'- mospheric air which is heatedfinthe lfurnace 9 and is then passed into the upper portion 4of the drying'y ltower 6 through a passage or duct 10. The furnace 9 may, for instance, be oil fired andl the air passing through it may beheated by causin it to pass along one side lof heat trans errin ir surfaces' which lon the other side are heated by direct contact with the products' of combustion. The heated air entering the upper portion of the tower contacts with the at'omized soap liquid issuingfrom the spray nozzles at `substantially its hottest temperature and, while drying of the soap particles is taking place, the drying air, the soap particles entrained therein and .the moisture absorbed in the lair pass downwardly through the drying tower in a compass out of the tower at the discharge opening 11 inintert Vmixed condition. This discharge stream ofmaterial-passes through duct 12 into col-'100 lector 13, here shown `as an ordinary cyclone collector, whereinthe collected solids are discharged through the hopper 14, and the eluent gas passes out through the duct 15. The residual solids entraine 'in the gas lthrough the'hoppers 17 at the bottom of the "collectors A conveyor 18, which may be ai screw conveyor, a'ineurnatic conveyor, or- 1 10v the like, is provide to receive the solids coming from the collectors and convey them continuously into the barrel or other package or storage reservoir 19. The .flow through the entire apparatus is established 115 by means of amotor operated fan 20 positioned at the dischargeside of the bag collector 1`6 and passing the gas drawn from the collectors 'to atmosphere through stack 21. y

The -particles of the sprayed liquid are carried in positive flow through the tower 6 by the drying gas, and thus every particle y is subjected ,to the drying treatment for substantially the saine length of time. on- 12b ditions in the tower are controlled by regulating'the temperature and amount. of the soap material passed into the tower and the temperature and amount of drying air supplied to the tower.- This, together with 180 los issuing from collector 13 are collected in' baci S collectors 16, the solids being discharged the concurrent flo`w of materials through the tower, effects a positive control of teniperatui'c and humidity conditions in the tower and permits the production of a uniform product of any desired moisture con tent. To further control the temperature conditions in the tower and particularly to restrict the evaporating action at the point where the moisture content of the soap particles has been reduced tov a desired amount and for the purpose of cooling the driedv particles to such extent as to render their collection in dry powder form feasible, a supply ot cooling air may be a'dmitted to the tower as indicated at 22. The tower may be designed for the admission ol' this cooling air at any one or more points along the length of the tower and, by way ot' example in the apparatus here shown, the cooling air is admitted near the bottom of the tower and consists of atmospheric air introduced by means of the power driven blower 23. In some instances it may be feasible to condition this air, as, for instance, by heating to a certain degree before admitting it to the tower. At the bottom of the tower 6 below the discharge opening 11 is a motor driven disintegrator 24 designed to receive any agglomerates oi' heavy. particles which may possibly be formed in commercial operation. Such heavy particles will not be drawn into the duct 11 but will dro into the disintegrator 24 where they Will e immediately broken up and caught in the air current which vis drawn into the disintegrator through the opening 25. This apparatus furnishes a means for carrying out the present process as a continuous operation which re uires no manual handling of the material rom the initial raw lstock to the finished powder product and, for that matter, tovpackage form ready for shipping.

As an instance of a specific embodiment of the process which has been employed successfully in the manufacture of a powdered ,soap the following conditions are given: An

ordinary boiled borax laundry soap was used. The soap stock was prepared hot, its temperature as passed to the spi-ay nozzles being about 220 F. The stock was prepared with about 10% solids. At this temperature and with this solid content the mixture" was very fiuid. In fact, a materially less amount of water and a lower preheating temperature can readily be used without reducing the soap mixture to a con` sistency so thick as to be objectionable. For economy of operation it is the best practice to preheat the liquid soap stock to as high a temperature as feasible and to prepare it` with as low a water content as will permit the ready handling and breaking up of the material into' a suitable spray, these conditions, of course, being regulated so as to be compatiblewth obtaining the desired qualities in the finished product and avoiding injury to the product. There is always a sufficient range between the moisture con-r tent of the material as sprayed and that of the finished soap for the reason that toilet soaps, laundry soaps and the like, usually contain only about 12% water in their commercial form. The physical factor which determines the amount of solids which can be present inthe soap as sprayed is tbe possibility of spraying or disintegrating the soap liquid into a proper spray. lVith an adequate preheating temperature soap stocks having a solid content as lighas may under certain conditions be successfully liandled. The best results in reducing the soap stock to a proper spray have been obtained in an air or steam atomizing nozzle designed to produce an umbrella-like spray. The object is to secure a finely divided uniform spray distributed uniformly across the space amount of moisture desired in the ultimate.

product. and the like. The iinal temperature is in a sense dependent on the product and must be sufficiently low'so that the product will not melt or be reduced to gummy or sticky condition. The reduction in temperature between the upper and lower portions of the drying tower is due largely to the evaporation of the moisture from the material under treatment. In the specific instance herein referred to a small quantity of atmospheric air was employed as a cooling medium.

The soap product produced under the conditions just stated is a light free-flowing apparently dry powder. It is uniform in appearance, is of uniform texture, is soft to the feel and exhibits complete freedom from particles of grit when rubbed between the fingers. When dropped into a pan of water the -product is readily dissolved without caking or lumping by a slight agitation, and it readily floats on the surface of the water.

The particles of the soap as they appear under the microscope are more or less irregular in shape. The particles are generally hollow to a certain degree. The substance of the particles is amorphous and continuous. Each particle is a unitary mass of material in contrast to a particle which is granular and which may be broken up into its composite parts. When the particles of the present product are disintegrated uiider the microscope they break up into irregular fragments qr plate-like pieces somewhat in the nature of the broken fragments of dried egg shells. The particle structure is analogous to that of hollow glass particles or bubbles in which the material of the particle is continuous and when disintegrated breaks up into fragments which are obviously broken out of a continuous mass which is itself unitary and is not in any sense an aggregate of component particles.

The present invention therefore provides a process for successfully producing commercially a dry, uniform, free flowing, fioating, nonscaking powdered soap, which process is continuous, requires a minimum of labor, makes possible accuratecontrol of all conditions which affect the character of the product and is fiexible in the sense that different sets of conditions can be,` established in continuous operation to thereby produce different grades of product.'

I claim:

1. The process of manufacturing a soap product in powder form which comprises preparing a soap stock in the condition of a reasonably free fiowing liquid, spraying' the said soap stock to present it in the form of a uniformly distributed liquid spray made up of small liquid drops of the same general order of magnitude in size and of generally globular form as in the case of true li uids as distinguished from the irregular ments of a disintegrated pasty material, entraining the drops of the sprayed soap stock in a downward] flowingcurrent of heated dryin gas which7 positively carries and propels tide said drops and the particles of soap resulting therefrom downwardly through the apparatus in like manner and direction of flow until uniform drying thereof is complete and separating and collecting the particles of the finished soap product from the said current of drying gas. y

2. The process of manufacturing soap in powder form which comprises preparing the soap in the form of a free flowing liquid stock, evaporating moisture from the' liquid stock by spraying it in the form of fine drops into the initial portion of a current of heated drying gas which entrains substantially all of y the said liquid drops and positively carries the said drops and the soap particles result- -ing therefrom along through the apparatus in like manner of flow While evaporation is taking place, whereby the said particles remain in suspension in the gas current until the moisture content thereof is reduced to the desired value and then separating thev rag- 3. The process of producing a finely .di-

vided powdered soap productw'hich com-` prises cornpounding the ingredientsof the product to form a relatively free flowing stock, spraying the said soap stock in the form of small independent drops into a current of heated drying gas at substantially the hottest portion thereof to thereby effect drying of said drops, positivelyI propelling the sprayed drops of soap stock and the dried particles of the soap productresulting therefrom throu h and out of the drying apparatus by sai current of drying gas, the. said particles being carried in and by the said gas current whereby every particle is subjected to substantially identical treatment in passing through the drying tower and a uniform product is obtained, regulating the relative amounts and temperatures of the liquid soap stock and the drying gas to produce an ultimate product of the desired moisture content and collecting the particles of the finished soap product from the current of reduced temperature spent drying y gas issuing from the drying tower.

4. The processof manufacturing a soap product in powder form which comprises preparing a soap stock containing all of the ingredients of the ultimate soap product in condition sufficiently liquid so that it can be disintegrated to a reasonably uniform finely divided condition in suspension in a gaseous drying medium, effecting such disintegration Ain a current of heated drying gas by atomizing to thereby effect evaporation of moisture from the said stock and reduce it to'the form of solidified apparently dry particles in suspension in the said gas, producing a positive and controlled movement of the finely divided soap stock through the drying apparatus by entrainment thereof in the said current of the gaseous medium to thereby effect substantially uniform drying of the respective soap particles, the evaporation of moisture therefrom taking place while the material is in finely divided suspension in the gas, restricting the drying `action whenthe material has reached an aping the said particles of the soap product from the resulting gas-current of reduced temperature.

,In testimony whereof I affix my signa.- ture.

ROBERT L. HOLLIDAY. 

